Conventionally, in order to define the flow rate of a transfusion to be injected into a patient, a transfusion pump has been used. The transfusion pump is attached to a transfusion circuit connecting a transfusion bag to a puncture needle and provides a transfusion tube constituting the transfusion circuit with a peristalsis, thereby feeding a transfusion at a set flow rate. Furthermore, generally, as the transfusion pump, a finger-type transfusion pump and a roller-type transfusion pump are known.
The finger-type transfusion pump includes a plurality of fingers arranged in a row along a transfusion tube, and allows the plurality of fingers to reciprocate separately, thereby providing the transfusion tube with a peristalsis. Furthermore, the roller-type transfusion pump includes a pair of rotation rollers and allows them to perform a circulation motion, thereby providing the transfusion pump with a peristalsis.
The injection of a transfusion using such transfusion pumps has a free-flow problem. The free-flow refers to the following: when a transfusion pump is removed while a clamp provided in the vicinity of a puncture needle of a transfusion tube is not closed after the process of transfusing is completed, a transfusion in an amount more than necessary is injected into a patient's body.
Furthermore, the free-flow problem may occur even in the case of the administration of a drug through a syringe pump. For example, in the case where a syringe is removed from a pump body when a patient pulls a drug tube or the like, a drug in an amount more than a defined amount may be injected into a patient. Furthermore, if a drug in an amount more than necessary is administered in the administration of a drug, the life of a patient may be threatened. Thus, to prevent free-flow is more important in the administration of a drug than in the process of transfusing.
In order to solve such a free-flow problem, for example, a transfusion pump equipped with an anti-free flow mechanism has been proposed for example, see Patent Document 1). The anti-free flow mechanism disclosed in Patent Document 1 is composed of an open/close device for opening/closing a dedicated clip previously attached to a transfusion tube. The open/close apparatus is contained in a transfusion pump body, and when a user opens an open/close door of a transfusion pump so as to remove the transfusion tube, the above-mentioned dedicated clip is closed automatically to crush the transfusion tube, thereby stopping the injection of a transfusion.
Accordingly, if the transfusion pump disclosed in Patent Document 1 is used, even if an attempt is made so as to remove the transfusion tube from the transfusion pump while a clamp is open, the injection of a transfusion into a patient in an amount more than necessary is suppressed by the anti-free flow mechanism.
In addition, as a method for preventing free-flow, it is conceivable to use a method for incorporating a valve apparatus that does not pass a fluid unless a pressure reaches a set value or higher in an injection circuit (for example, see Patent Document 2). In the injection circuit in which the valve apparatus is incorporated, it is considered that a fluid does not flow at a low pressure (head pressure) at a time free-flow occurs, so that free-flow can be prevented.
Patent Document 1: JP 2004-73822 A
Patent Document 2: JP 2004-501686 A